Coded signaling apparatus



2 Sheets-Sheet 2 Filed May 9, 1947 mm Aww m. www I@ Kw Jl AL JN .f W na QN ,mm NMR J1 N wm M SN@ W aww@ JM* mm@ MNE n sw m m ww p1 lm 1.11% md u Ir, lr D.. W H m wy m 11 N@ jatented Feb. 28, 1.950

I'TED y IS"I'igTE-Sl PTEN T O F Fl CE QG'ODED ASIG'NALING APPARATUS vHoward rAfThomps'cm Edgewood, Ba., assigner 'to The Union Switch & Signal "Company, "Swissvale, Pa., a "corporation of -lennsylvania Applicatinnimay 9, 1947;,.seria1.Nds/46,969

.My .invention relates to coded .signaling P- paratus.

An `object of .my invention .is to provide .improved means for detectingcode .following operation .of a-code following relay.

Another .object .of .my invention .is lto lprovide improved code detecting means which will .not be .improperly .energized in the .event .the c'ontacts of the code following relay overlap.

An ladditional object of .my .invention is .to A4provide improved code .detecting .means .which will not .respond until the code following .relay has completed a predetermined lnumber of .cycles .of operation, but which will .respond quick'ly 'to ya cessation of operationof the code `fo`llovving relay. A still further .object of .my invention Sis 'to provide a novel arrangement ,of counting chain relays for decoding .coded .impulses of energy.

Another .object of my invention is yto .provide a coded track circuit `signaling system of the count .code type utilizing a .novel arrangement of counting chainrelays and code .detectingrelays wherein a .detectorcode and a control code .may be transmitted concurrently over the section rails, and arranged .so 4that the display of are'- strictive indication is .not :delayed by the lenglth of .a control code cycle, 'but is .governed 'by the faster detector code. y

Other objects .of the .invention .and .'feature's of novelty will be .apparent 4from the following description .taken in connection with theaccoin- .panying drawings.

I vshall .describe a "few Vforms vof coded signal apparatus embodying my invention and 'shall then point out the novel lfeatures .thereof in claims.

In the drawings,

Fig. 1 is a diagrammatic view of code .detecting apparatus embodying my invention,

Fig. .2 shows a modification of 'the arrangement shown in'Fig. l1,

' Fig. 3 is .a diagrammatic view df code detect-- ving apparatus embodyingmyinventionfor delaying the response of vthe code detecting means until 'the code .following relay lhas operate'd through several cycles, and

denser to which energy is supplied when "the contacts of the .code following relay are in one `position 'and ifrom 'which energy is supplied@ a slow lrelease code detecting relay when the-con tacts iofthe code following `relay lare .in .their other position, fthe relay and condenser .being connected .-in series, and having .an vasymmetric unit, such :as .a -rectier v.or 4other device, .for by.- pa-ssing the winding .of the .relay while .the iconydenser -is :being charged. .The .asymmetric 4unit -po'led fso --that lwhile :the .condenseris discharging energy will liow through the .winding of the slow release .code .detector relay, causing .it to pick This detector .relay `is slow .in `release- 'in'g .so :that :its 'cnntacts v.will .remain picked up 'during ith'e intervals rin which .energy ,is not .suplplied-lto .its winding.

. Furthenl -extendthe .principle explained above ato provide .a chain .of :relays which are :energized linseduence as a result :of Acharging condensers associated atherewith and :discharging .the con- .d'ensers .through ztheir associated relays, in accordance .with .the .operation .of the .contacts of .-a code following relay. .A .counting chain thus onstructed .is iused .to :delay `the pick-up of a first auxiliary relay, which .after picking up, establishes a-stickicircuit vfor itself `and interrupts the circuit for the =counting .chain relays, and fthereafterin conjunction with a second auxiliary -relayiunctions :in the manner of the Well-known FSA-.BSA method of lcode detection. iFurtheriex-tended, athecounting .chain described uabove fmay be .used .for `the detection .and .decod- .ing of control code energy consisting ofrecurring l-cycles -zef coded :energy .having a predetermined .number Ior control code .pulses in each control lcode lcycle. .The .system .embodying this .counting chain is arranged .so that a detector .code "and a control code are transmittedconcurrently v:and operate separate `code kfollowing vrelays Vreach :of which governsdecoding .mea-ns. rEhe detector code has ka much .shorter code cycle than Vthe -control code .so the .detector -code decoding means has amuch shorter .releasedelay period than .the control code decoding means. 'The two setsv of `decoding .means `cooperate to control a .signal 4in .such manner that the .most .restrictive .indica- Vtion is displayed when .the .detector code decoding .means .is released to thereby insure prompt display of this indication when'the supply .oi coded energy is interrupted.

In Fig. 1 o'f the drawings, there is shown fa stretch of railroad r.track 'having track rails t9 and Il which are divided 4by linsulated 'joints I2 into the customary track sections. 'Onecomy.plete section '6T, and portions of the adjoining sections A5T and "1T are shown. Tra'c normally vmoves fromleft 'to right vin the trac'k stretch and a signal GS is located at the entrance end of section 6T and governs entrance of traffic into the section. A contact of a continuously operating code transmitter BCT recurrently connects the track battery BTB across the track rails at the exit end of section T. The contact of code transmitter BCT may operate at any appropriate.

code speed, such as 75 times a minute, while the energy supplied to the section rails operates a codefollowing track relay STR, the winding of which is connected across the section rails adjacent the entrance end of the section.

When the contact of code transmitter 6CT is closed and the section is vacant, energy from the battery STB picks up the contact of track relay GTR with the result that energy is supplied from terminal B of a source of direct current, not

shown, over front contact I5 of relay ISTR.,V

through asymmetric unit I5, and resistance II to one element of a condenser Q, the other element of which is connected to terminal C of the same source of direct current. Accordingly, during the picked-up periods of track relay ETR. energy is supplied to the condenser Q and charges the condenser. The resistor II limits the energy supplied to the condenser Q and thus limits the current supplied through contact l5 on initial closing of this contact.

When the contact of code transmitter SCT interrupts the circuit of battery BTB, the relay TR releases and its contact l5 interrupts the supply of energy to the condenser Q and establishes the circuit Ior supplying energy irom condenser Q to code detecting relay Isl-I. This circuit is traced from the left-hand element of condenser Q through resistor Il, winding or relay lill-I, and back contact I5 of relay TR to the right-hand element of the condenser Q. The energy supplied from condenser Q to the winding of relay cH picks up the relay contact 2U to interrupt the circuit of the red lamp R and establish the circuit of the green lamp G of signal BS.

During the next picked-up period of track relay STR the circuit for Supplying energy from condenser Q to relay 6H is interrupted while energy is again supplied to the condenser through asymmetric unit I5 over the circuit traced above. At this time the asymmetric unit I5 serves as a snubbing unit to retard release of relay 6H so that -the relay contact 2t remains picked up in the periods during which the supply of energy to `the relay is interrupted. In addition, the asym'- metric unit I5 has very low resistance to -fiow of Q. Accordingly, the energy stored in the condenser discharges through the relay 6H after which the relay 6H releases and contact 20 interrupts the circuit of the green lamp G and establishes the circuit of the red lamp R of signal GS so the signal indicates that the section is occupied.

An adjustable resistor 2I is connected across the terminals of the condenser Q and serves to limit the charge on the condenser. The resistor 2l also provides a path through which energy stored in the condenser may discharge when the supply of energy to the condenser is cut 01T. According- 1y, the resistor ZI limits the period during which the energy supplied from the condenser to the relay 6H' keeps the contact 20 picked up after y y shunting of the track relay ETR.

current from left to right with the result that periods of the track relay and energy stored in the condenser is supplied to relay 6H during the released periods of the track relay, while the re'- lay 6H is slow enough in releasing to remain rpicked up during the picked-up periods of the track relay so contact 20 maintains the circuit of the green lamp G of signal BS.

When a train enters section 6T, the track relay STR is shunted and ceases to respond to coded energy and its contact I5 no longer establishes the circuit for supplying energy to the condenser y When the section is vacated, the track relay GTR is again operated by coded energy so the condenser Q is charged during the picked-up periods of the relay and energy from the condenseris supplied to relay 6H during the released periods of the track relay so contact 20 again establishes the circuit of the green lamp G.

The equipment is arranged so that the relay 5H will not be picked up if movable contact I5 of track relay i'IR. engages both its front and back points of contact at a time when the track 'relay is shunted. Under these conditions terminal B of the source is connected over contact I5 of relay STR. and through rectier or asymmetric unit It and resistance I1 to one element of the condenser Q, While terminal B of the source is also connected through front and back contacts of track relay contact I5 to the other element of the condenser Q. Accordingly, the condenser will not be charged and energy cannot be supplied from the condenser to the relay 6H and the relay '6H is certain to remain released. k

Ii the condenser Q breaks down so that a circuit is established between the elements of the condenser, energy Will not be stored in the condenser and therefore cannot be supplied from the condenser to the relay 6H so the relay is certain to remain released. If the condenser Q breaks down, the relay 6H will not be energized during the v.picked-up periods of the track relay as the asymmetric unit IB provides a 10W resistance shunt across the terminals of the Winding of relay 6H.

If the asymmetric unit or rectifier I5 breaks down, it will form a low resistance shunt across the terminals of the Winding of relay 5H during the time energy is being supplied from the con' denser Q, and insufcient energy will be supplied.

to the relay 6H to pick up its contact so the contact 20 remains released.

If the circuit of the asymmetric unit or rectier I6 is open energy will be supplied from left to right through the winding of relay 6H during the picked-up periods of relay STR, and Will be supplied from right to left through the Winding of relay 6H during the released periods of relay STR. The relay 6H is a direct current relay and' its contacts Will not be picked up as a result of the supply to the relay winding of impulses of energy of alternately opposite polarity. Accord,-

ingly, if the asymmetric unit or rectier I6 is open-circuited, the relay 6H will remain released and cause signal GS to display its stop indication.

From the foregoing it will be seen that the relay GH is energized when the track relay GTR is operated by coded energy, but will not be energized if thefront and back contacts of the track relay overlap so as kto engage the movable contact simultaneously, while the relay 6H will not be en- `ergized if the condenser Q or the asymmetric unit @mim iis defective. Accordingly, any :ifailure fof p-the equipment lwill result in release .of relay BH vto cause Ithe Ared or ydanger lamp to be lighted and cannot A-result vin improper energization of relay SH Awithconsequent.lighting ofthe green .or clear lnxnpof Ithe signal BS.

In Fig. 2-of the drawings, there is shown therein a; modication .of lthe apparatus shown in Fig. 1. Thefarrangement-of equipment in Fig. 2` issimilar tofthatlshown in Fig. 1, except that a contact of relay ETR instead of .an asymmetric Aunit Vis'employedto prevent flow ofenergy through the Winding-of `relay during charging of the condenser Q and 'to-"cause energy to flow through the relay windingduring dischargeof the condenser. The equipment isshown in the condition which it assumesiwhen the track stretch is Vacant. .At this time relay STR operates in response `to `the impulses of `coded energy supplied thereto over the Vsection rails IU and fl I.

Whenthe contacts of Arelay STR -pick up, lenergy issupplied to one element of the condenser Q by a circuit which -is traced from terminal B over front contact :I5 of relay GTR, front contact vI8 of relay ETR, and through the resistor I'l to vthe left-hand element of condenser Q, the right-hand element :of which is connected to terminal C. Accordingly, fduring vthe picked-up periods of track relay ASTR. @energy is supplied-to the condenser Q and charges thecondenser.

When the contact of code .transmitter GCT interrupts the circuit of .battery STB, the relay STR releases and its contacts I5 and I 8 interrupt :the supply of energy to the condenser Q and :establish the circuit for supplying energy from condenser 'Q to code detecting relay 6H. This circuit is traced from the left-hand element of y.condenser Q'through resistor I "I, winding of'relay *back-contact "IB of relay GTR, and Yback con- '.tact AI'5 of relay GTR 'tothe right-hand element of condenser Q. The energy `supplied from vcon- Hdenser Q to the winding of relay `ISH picks up the :relay 'contact 20 to interrupt the circuit o'f vthe red lamp Rand establish the circuit of the green 'lamp G vof signal 15S.

During the next picked-up period of track relay "GTR the circuit for supplying energy from condenser Q 'to relay 6H is interrupted While l'energy'is again supplied to the condenser through the circuit traced above including the front con- "tact l'of relay-GTR.

As long `as relay GTR responds to coded energy fthe `condenser 'Q is charged Aduring the picked-up periods of the 'track relay and energy stored vln thecondenser-is discharged through the winding of relay lI-l during the released periods of 'the track relay, while lthe relay `IiH'is of 'a type which is slow enough in releasing to remain picked up :during the ,picked-up periods of the track relay 'so contact 20 maintains the circuit of the green lamp G ofthe rsignal ES.

'When a train enters section '6T,'the track Vre- .lay 'ETR 'is shunted `and ceases to respond to coded v'energy and its contacts I5 and I8 no longer es- "tablish 'the circuit for supplying energy to the "condenser Q. Accordingly, the venergy stored in l:the condenser discharges through the relay 6H after which the relay BH releases and contact 20 .interrupts the circuit of the green lamp G and :establishes 4the circuit of the red lamp R of signallS.

When the section is vacated, the track relay ISTR. is again operated vby coded energy so the condenser Q 'is charged during the picked-up 'periods fof the 'relay vand energy from the lcon- '6 denseris supplied vto :relay .6H rduringthe released periods -o the track frelay so :contact 20 ...again establishes 'the circuit .of `the .green lamp Gr .of signal `(iS.

The :equipment :is arranged .so that the .relay 6H will not be picked up if movable :contact yI5 engages both its front andback .points 'of contact at atime rwhenthe trackrelay is shunted. Under theseconditions terminal .-Bof the .source is connected over contact .I5 of relay GTR .and through rontcontact I Bof Arelay BTRto the left-handelement o'f condenser Q while terminal :B of the source is .also yconnected through .front and yhack contacts of track .relay .contact I5 to the .righthand element .of condenser Q. Accordingly, the condenser Q -will'nottbe charged and energy .cannot be supplied from 'the condenser Ato the 'relay '6H-and the relay 6H is certain to release andfremain released.

-If Ithe condenser lQ breaks downso that a circuit is established between .the elements of 'the condenser, energy will not be Lstored inthe condenser and therefore cannot .besupplied Afrom the condenser tothe vrelay l6H so the relay is certain to remain released. If the condenser Q breaks down, the relay 6H will not be .energized during the 4picked-up periods of the track relay as the contact I8 of relay GTR will interrupt Lthe circuit.

I1 Athe movable contact yI8 of relay BTRfshould engage both its front and back points of contact at -a time when the track relay is shunted, :it will 'be seen that vthe winding of .relay Vlil-l is `thereby shunted, and insuicient .energy will be supplied to relay 6H to pick Vup .its contacts so `contact .20 'remains released.

'From the foregoing it `will be seen that with the equipment embodying my inventionarranged as shown in Fig. 2, the relay 6H is energized when the track relay vESTR is operated by coded energy, but will not be energized if the front and back contacts of either of the movable con` tacts of the track vrelay overlap so as to engage lthe movable contact simultaneously, while the relay y6H will lnot be energized if vthe condenser -Q is defective. Accordingly, any failure ofthe equipment .will result inthe release of relay 6H to cause the red or danger lamp of Vsignal .BS to be lighted and .cannot result in improper enerfgization `oi 'relay 6H :with Aconsequent .lighting of lthe green or clear 'lamp of the signal GS.

'In some situations it is desirable on initiation lof coding voperation of -azrelay to delay establish- "ment of Ia control circuit until there have been v4a predetermined number of operations of the Vcode following relay, but to interrupt the con trol circuit promptly on cessation of coding Aoperation of the code following relay, and Fig. 3 is Aa ldiagram showing equipment arranged to .provide this vmethod of operation.

The equipment of Fig. 3 is similar v*to that of Fig. l and is shown in the condition `which 'it assumes when the track stretch is vacant. During the picked-up periods of -track vrelay STR 4energy is supplied over its front contact 3U, front contact 3| of a rst auxiliary relay JBHD, vand through rectifier or asymmetric unit K4 to charge vcondenser Q4, while at this time energy .stored in the condenser Q5 is supplied to the winding -of a second auxiliary relay GBSA over the circuit which includes front Contact 32 of yrelay SHD and fronticontact 33 of relay ISTR.

During the released Vperiods of relay GTR the vcircuits vrfor supplying energy to condenser "Q4,

and for supplying energy :from condenser Q5 'to :relay GBSA are interrupted, 'while Ienergy ils amanda 7 supplied from condenser Q4 over the circuit which is traced from the left-hand element ofthe condenser through the winding of relay BHD, over front contact 3l of relay BHD and over back contact 33 of relay BTR to the other element of vthe condenser.

In addition, during the released period of track relay BTR energy is supplied to condenser Q5 over the circuit which includes back contact 30 of relay BTR, front contact 32 of relay BHD, and asymmetric unit K5, and a charge is developed in the condenser Q5 so that energy may be supplied therefrom torelay BBSA during the subsequent picked-up period of relay BTR.

The energy supplied to relay BHD during the -released periods of track lrelay BTR keeps the relay contacts picked up and the relay is slow enough in releasing to remain picked up during the picked-up periods of the track relay. Similarly, the energy supplied to relay BBSAduring the picked-up periods of the track relay BTR keeps the relay contacts picked up and the relay condensers during the picked-up periods of track relay STR, nor can energy be supplied from rthese condensers to relays SHA, BHB and BHC during the released periods of track relay BTR. Accordingly, the relays BHA, BHB and BHC remain released.

If a train enters section BT, the track relay BTR is shunted and remains released with the result that contact 33 interrupts the circuit for supplying energy to relay BBSA and after a short time interval the relay contact 35 releases and interrupts the circuit of the green lamp G and establishes the circuit of the red lamp R. In addition, after release of relay STR energy is supplied from condenser Q4 to relay BHD over the circuit established by back contact 33 of track relay ETR, but the energy from the condenser is soon exhausted and the relay BHD thereafter releases so that its contact 3l interrupts the circuit shunting contact 3'I of relay BHC, while contact 32 interrupts the circuits of condenser Q5 and relay BBSA, and contact 36 establishes the circuits of condensers QI, Q2 and Q3 and of relays SHA, BHB and BHC.

When the section is vacated, the track relay STR again responds to coded energy and during the first picked-up periods of the track relay contacts energy is supplied to condenser QI over the circuit which is traced from terminal B over front contact 30 of relay ETR, through asymmetric unit KI to one element of condenser QI, and from the other element of this condenser over back contact 3B of relay BHD to terminal C of the source. During the first released period 'of the track relay STR, the supply of energy to condenser QE is interrupted While energy is supplied from this condenser to relay BHA over the circuit which is traced from the left-hand element of the condenser through the winding of relay BHA, over back contact33 of relay BTR and back contact 36 of relay BHD to the other element of the condenser QI. The energy supplied to relay BHA picks up the relay contact 38 `Q3 so that energy cannot be supplied to these so thatfduring the next or second pickedfup pes riodof the track relay contact 3U energy is sup-,- plied not only to condenser QI but is suppliedalso. over front contact 38 of relay BHA to condenserv Q2 with the result that during the next or second released period of the track relay BTR energy is supplied from condenser QI to relay BHA and is also supplied from condenser Q2 to relay BHB over the circuit which includes frontcontact 3 8y of relay BHA, back contact 33 of relay STR and,v back contact 3B of relay BHD. The energy supey plied to relay BHA holds contact 38 picked upA while the energy supplied to relay BHB picksY up its contact 4D so that during the next or third picked-up period of track relay BTR energyvis suppliedv to condenser Q3 as well as to condensers QI and Q2. During the next or third released period of the relay BTR energy is supplied from condenser Q3 to relay BHC to pick up its contact 31, while energy is supplied from condensers QI and Q2 to relays BHA and BHB to hold their contacts picked up. g,

During the next or fourth picked-up period of the track relay BTR energy is supplied to,con,

densers QI, Q2 and Q3, and is also supplied to condenser Q4 over the circuit which includes front contact 31 of relay BHC, while during the next or fourth released period of the track relay energy is supplied from condenser Q4 to relay BHD and its contacts pick up so that contact 3| establishes the connection shunting contact 3l of relay BHC in the circuits of relay BHD and' condenser Q4. In addition, when relay BHD picks up, its contact 3B interrupts the circuits of conf densers QI, Q2 and Q3 so that energy is n longer supplied from these condensers to the associated relays and after a period thefrelays BHA, BHB and BHC release, while energy remain; ing in the condensers is discharged through the resistors which are connected across the ccnl denser terminals.

After picking up of relay BHD energy is supplied over its front contact 32 to the condenser Q5 during the remainder of the released period. ci contact 3B of track relay BTR so that during the next o-r fifth picked-up period of the contactsof track relay BTR energy is supplied from cogn denser Q5 to relay BBSA over the previously traced circuit for this relay and its contact 35 picks up to interrupt the circuit of the red lamp R and to establish the circuit of the green lampl G. On continued code following operation of the track relay the condensers Q4 and Q5 are alter nately charged and the relays BHD and BBSA are alternately energized so the relay 5BSA..main tains the circuit of the lamp G.

From the foregoing it will be seen that on initiation of code following operation of the track relay BTR at a time when the auxiliary relays BHD and BBSA are released, the relay BBSA re,- mains released until the track relay picks up for the fifth time. Accordingly, if, while relays BHD and BBSA are released, the train fails to shunt the track relay momentarily and the track relay responds to one or two impulses of coded .energy,. the relays BHA and BHB may become picked up, but the relay BBSA will remainre; leased and maintain the circuit of the red lamp R and there is no possibility that the circuit of the yg the section. Where track relay STR is shunted .and .remains released, the circuit `for supplying .energy from condenser Q to relay BBSA is in- .terruptedand the relay BBSA releases after a .shorttimeinterval so thatthe `circuit of the red .lamp .R is established promptly after entrance SBSA, While after release of relay BHD the relay VSBSA can bereenergized only -as a result of continued code following operation oi the .track relay GTR.

.Although three stepping relays are shown in -addition to relay GHD with the result that ve `cperations of the .track relay STR are required topick-up therelay BBSA, it should be understood .that a .larger or .a smaller number of stepping `.relays vmay be provided if desired to thereby cause relay .EBSA to pick up'inresponse to a larger `or fazsmaller number of operations of the track relay.

.Thexcombination shown in Fig. 3 provides protection against .improper energization of relay SBSA in the event thecontacts of relay GTR, `are defective. If.movable contact 3D of relay 'GTR rsimultaneously.engages its front and back points ofccontact, the battery willbe short-circuited if contact .33 engages .either its front or its back contact. Similarly, if movable contact 33 of relay BTRshould simultaneously engage both its .front landback points of-contact the battery is sh0rt- :crrcuitedif contact 30 engages either its front or its -back contact. When the battery is short-cirrcuited, energy will not be suppliedthereirom to .therelay16BSA andit .will be released 'and will .interrupt the circuit of the green lamp G and :establish the circuit of the red .lamp R).

Tlf the contacts ofrelay STR are out of adjustment so thatfront contact 30 and vback contact 33 areclosedat-'the same time, the batterywill be shortcircuited- Similarly, if back contactalland 'fr-ont contact 33 are closed at the same time,the "battery will be short-circuited and relay GBS?. will .remain released.

:Likewisefasexplained in `connection with Fig. 1, .the relaysBHD .and SBSA `will remainreleased if :an asymmetric `unit `or condenser associated (therewith .is defective.

y wIii-Fig. 4 of the drawings there is shown a lio modifledform of code detecting means embodving lzthisinvention and arrangedto -selectively control arsignalimaccordance with .the number of im- Vpulses of energy supplied over the rails of aseo- .tion 4during onecycle of operation of .the code transmitting means. Thecombinationshown in '.Fig. .4..is.also arranged .to insure prompt V.display of Ithe stop yindication in the event the supply of Acoded energyover ythe rails vof va track sectionis interrupted,

.Referring to .Fig-4. it .will beseen that Ytrack Irelays BRTR .and 6NTRare connected in series 'across the .section 4rails .adjacent 4the ventrance zend of-.the section. Therelays BRTR. and .ENTR vsare of. the vpolar `biased neutral type and each 1 has zcontamts which .normally "occupy their vreleased mosition vfrom .which they are moved to their 'picked-up position when and -only when energy "ilowsthrough the `relayvvinding in a Yselected direction vas indicated bv the arrow on vthe relay winding. The 'relays BRTR and ENTR. are con- Lnectede across the itracklfrails sov that theygrespond to energy :1 impulses :of :opposite relative` polarity, mae ',.irelay :GRTI'R'fbeing operated `by 'impulses of immerse. polarity, :that is, when :the :track rail I I nll-.O is .positive withrespect to trackrail I0, and the relay ENTR being operated by impulses of normal polarity.

The relay BRTR controls relays BRFR and SRBR While the "relay SNTR. .controls repeater relays 6NFI, VliNFZ, .6NF3, .6NF4, SNBI, 6NB2, 6NB3 and BNBL rThe repeater relays GNFI, BNFZ, .6NF3 and SNFI cooperate with relay BRBR 'to control'slow releaselrelays SFIP, BF2P, EFSP and GF4? which control the circuits of the lampso'f signal GS.

The supply ofimpulses of .energy to the section rails is governed by a code transmitter ECTwhich lhasa plurality of cam wheels whichare continuously rotated-ata suitable rate. The-cam 4wheels are designated I, II, IIIe-nd IV, and eaohhas on `.the periphery :thereof six projections vwhich .are separated by six recesses. The projectionsfmay be of either full Vor one-half height and .control movable contact :members in such manner that when the cam "follower on a contactimember engages the recessed surface between projections, the contact establishes a circuit over which energy rof'reverse vpolarity may be supplied from the-battery BRTB to the section rails. When the cam vfollower on a contact member'engages a projection 'of one-half height, the contact meinberlinlterrupts the circuits of `both 'of -the batteries LSNTB and 'SRTB and'thus cuts 'off the supplyp energy yto the section railsybutvvhen thefcam'folllower on a `contact memberfengages'a projection 'of full height, the contact establishes a `circuit: over which energy of normal polarity may besupplied from .the battery GNTB to thesectionrails.

As each of the cam wheels has six recesses, anti `as. energy of reverse polarity is supplied tothe section .rails when a camfollower'engages va recessed surface, it follows that six impulses of energy of vreverse polarity are supplied tofthese'c- .tion'rails during .each revolution of a cam wheel.

lThe impulses vof 'energy of reverse Apolarity are separated '.by intervals during which-impulses of venergy of normal 'polarity are supplied 'to the section rails, or in which the supply of energy to the sectionxrails is cut oil, depending on the arrangement of the'projections which separate the'recesses on 'the periphery of the cam wheels.

As .hereinafter explained the impulses of'track circuit :energy ofzreversepolarity supplied yto the section'rails'serve as -a'detector code and operate :track relay-SRTR to indicate `v'zhetherfornotthe sectionis occupied. Each impulse of track circuit energy of reverse polarity together with yan accompanying interval in which energy 'of reverse polarity is vnot supplied l constitutes one cycle of detector'code energy, and as six impulses .of energy ofreverse Apolarity are-supplied during lheight...and'iive projections of one-half height r,with the 4:resultgthat when this cam wheel con- 'h'.lsithe supply of tenergy to the Ysection :rails .the 'six iirn'pulsesl of energy :of .reverse polarity 'supplied during one :revolution `of the cam wheel asieaaoa arefsepar'ated by one impulse of energy of no rmal polarity and by ve intervals during which the supply of energy to the track rails is cut off. The cam wheel II has two projections of full height located adjacent each other, and four projections of one-half height and when this cam wheel controls the supply of energy to the section y,rails the six impulses of energy of reverse polarity ,supplied during one revolution of the cam wheel are separated by two impulses of energy of.normal polarity and by four intervals during which the Isupply of energy tothe track rails is cut oi. i i v The cam wheel III has three projections of full height located adjacent each other and three provlections of one-half height and when this icam wheel governs the supply of energy to the section rails the six impulses of energy of reverse polarity supplied during each revolution of the cam wheel are separated by three impulses of energy of normal polarity and by three intervals during which the supply of energy to the track rails is cut off.

The cam wheel IV has fourprojections of full height located adjacent each other and two projections of one-half `height andwhen this cam wheel controls the supply of energy to the section rails the six impulses of energy of reverse polarity supplied during one revolution'of the cam wheel are separated by four impulses of energy of normal polarity and by two intervals `during which the supply of energyto the track rails is cut 01T.

The circuits governed by thecam wheels I.II, III, and IV are controlled by relays 1FlP, 1F21), 1F31 and 1F4P, not shown, which are governed by traiiic conditions in advance in substantially the same manner as the relays GFIP, BFZP, SFSP and 6F4P.

The equipment is shown in the condition which it assumes when the track stretch is vacant. At this time the relay 1F4P is picked up and its contact 45 connects track rail Il to the movable contact associated with cam wheel IV. As explained above, during each revolution of this cam wheel there are supplied to the section rails six impulses of energy of reverse polarity which are separated by six intervals. during four of whichenergy of normal polarity is supplied to the section rails and during the remaining two intervals the supply of energy to the track rails is cut off.

During the supply of each impulse of energy ofreverse polarity over the section rails the contacts of the relay SRTR pick up and those of relay ENTR remain released. During theintervals between impulses of energy of reverse polarity supplied over the section rails the. contacts of relay GRTR release. During the picked-up period of the contacts of relay GR'I'R energy is supplied from terminal B of a local source of direct current over front contact 46 of relay BRTR, and

through the asymmetric unit KI D to one terminal of the condenser QI 0, the other terminal of which is connected. to terminal C of the source. Ac,-

4cordingly, a charge is built up in this condenser and during the released period of relay GRTR energy from the condenser is supplied through the winding of relay GRFR over the circuit which includes back contact 41. of relay BRTR. This energy picks up the contacts of relay GRFR, while the rectier KH) snubs the. winding vof relay RFR and renders the relayrslow enough in releasing to cause its. contacts4 to' remain, picked up during the picked-up periods of relay GRTR.

When front contact 48* of relay SRFR is'closed', energy is suppliedl through asymmetric unit KAII to condenser QH during the released periodsfof contact 46 of relay SR'IR, and during the pickedf up periods of relay SRTR energy from the conf'j denser QH is supplied through the Winding of relay BRBR over thejcircuit which includes front Contact 4l of relay ERTR. The energy supplied to relay GRBR from condenser QH picksupfthe relay contact, while the relay isvsnubbed byrec'tif er KI I andl is slow enough'in releasing to remain picked up during the released' periods of relay GRTR. i

.Since six impulses of energy of reverse polarity are supplied overthe. section rails during each revolution of any one of the cam wheels the in-t tervals between vthese impulses are relatively short, andthe .release time of relays SRFR and GRBR does not need to be very long to insure that these relays will remain picked up as long as relay SRTR is operated by coded energy. Ac#- cordingly, if relay BRTRceases to be operated by coded energy, as is the case when a train enters the section, the relays RFR and SRBR will releasev promptly and willv cause prompt display of the stop indication by signal GS, as explained in detail below. However, as long as the section is vacant and impulses of energy of reverse polarity are supplied over the section rails, the relays BRFR and SRBR are picked up and front contactvll of relayA BRBR in the circuits of 'relays BFIP, GFZP, 6F3P and 6F41 is closed.

Since the control code cycle determined by each of the cam wheels ,contains 6 negative impulses, it will be seenthat as long as the track section is vacant the equipment including relays ERTR, SRFR and SRBR will operate as described above, and for purposes of brevity, the description of operation of that portion of the equipment will not be repeated hereafter.Y 1 As shown, the relays IFAP and 1F3P are both picked up so that the supply of energy tothe rails of section 6T is, governed by the cam wheel IV. As illustrated, themovable contact associated with cam wheel IV engages a projectionof full height so that the contact establishes a circuit for supplying energy of normal polarity from the battery BNTB to the track rails. This energy feeds over the track rails and picks up the relay ENTR with the result that when the relays NF and NB are all released, as shown in the drawings, energy is supplied over front contact 5,2 of relay ENTR, through the rectier Ki 2 over back contact 53 of relay SNFB and back contact 54 of relay 6Nl4 to one element of condenser Q2i so a charge is built up in this condenser. y

On movement of the cam wheel IV the movable Contact governed thereby interrupts the circuit 'of the battery @NTB and establishes the circuit of Ythe battery ERTB with the result that'relay GNTR releases and relay SRTR picks up. When relay GNTR releases, contact 52 of relay ENTR. interrupts thesupply of energy to condenser QZI and contact 56 of relay ENTR establishes a circuit for supplying energy from condenser Q2I 'to relay BNFI over the circuit which is tracedV from the left-hand element of the condenser over back contact 54 of relay 6NF4, back contact 53 of relay 6N'F3, back contact 5l of relay BNFZ, winding of relay SNFI, and over back contacte of relay GNTR to terminal C and thus to the other element of the condenser QZI. The energy supplied from condenser Q2| to relay BNFI picks up its con--l .tact so thatduring the remainder of the released period of the relay BNTR energy is supplied "to condenser: Q22` over the circuit' which is from terminal Blof the' sourceover' back contact' 520i relay GNTR, front'contact58 of' relay GNFI, and" through the asymmetric unit KI3 to one terminalV of the condenserQZZ, the other terminal of Which is connected to terminal C of the source'. Accordingly, a chargeis built up in condenser Q22'.

On further movement of the camwheel IV-v the `movable contact associated therewith., engages the second projection of' full height so thatvthe contact interrupts the circuit'of'th'e battery'BRTB and' establishes the circuit of the batteryA ENTB withl the result' that' theA contacts of relay'- ENTR; pick up so'vthat' contact 58" interrupts theY circuit traced' above for supplying'energy'from condenser Q2| to relay BNFI and establishes the circuit'ifor` supplying energy from condenser' Q22 to' relay EN'BI This' circuit4 is traced" froml the left-hand terminalV offthe condenser Q22'over'back contact 5,93 of" relay SNBZ, through the winding' of* relay BNB-Ii, over' front" contact 58 of" relay# SNFI and front contact55 offrelay' SNTR' torterminalC and' thus t'o the other element'offcond'enser Q22. The energy suppliedy torelay SNB'I picks' up the-relay contact 6U' so' that during the remainder of this' second pickedfupiperiodof relay SNTE-energy is supplied to condenser Q23 over the circuitiwhich is traced from terminalBovler iront' contact' 52z of` relay ENTR, front" contact 60of' relay 6NB1', and

' through asymmetric unit KM to onez element of' the condenser Q23; the'- other elementiof which is-r connected to terminal C'of the source. Atths: time` energyl is also` supplied tov condenser: Q24: over' the` circuit previously traced'.

On further movement' of' the camv wheell IV the` movabley contact: associated therewith interrupts the* circuitiof thebatt'ery GNTB and.' establishes their circuit of theL battery' GRTB' with' th'el result that' relayI GNTR releases and relay'BRTR picks up. vWhen relay SNTE. releases', contact 52.' of relay` ENTR interrupts'` the supply' of' energy' to condensers'fQZli an'dQZSf and contact 5B of relay` ENTR establishesa circuit" for supplying energy from condenser Q23 to relayfGNFZ overthe circuit" which isitraced' from' the left-hand element of condenser Q23` over back? contact 62 of' relay SNES, through the'. Windingl of relay GNFZ; over front: contact lill7 off relay BNBI, and overv back contact' 56- of: relay ENTR to terminal-r C f and: thus to the other element of condenser: Q23. The-energysupplied to relay GNF! pickslup'the'conta'cts ofthe relay* and contact 51" of relay' (iNlEiZ'y inter rupts theA circuit' for' supplying: energy to' relayl BNF is from'` condenser'- Q21; and'. the?.l energy'y stored in condenserl Q21 i'stdissi'pate'd by the1-r,esistorfconr rrectedaround its elements:

' Fu rth'errn'ore', Wherr relay '6NF2zpi'Cks' 'upy itsfc'on'- tact 51' interrupts the circuit: byi'whichrectifier K12 is: connected` across the' terminals of? the' winding off relay GNPI" sothe-:rectifler K lf2 ceases to v snub the' relay SNF l*l and it releases7 promptly after' picking' up of' relay' GN'EZ. When relay BNF! releases' its' contact' 58 interruptsthecir'- cuit. for supplying: energy'to c'ondenser`Q22- and establishes the circuitnor` supplying AenergyctoA the condenser Q24. This circuit is tracedyfromiterminal B-over backl contact52zofre'lay'6NTR, back Contact' 58 of relay GNEI, front Contact ofre'- lay' BNF?, and` through` asymmetric'v unit' K] 5: to one element'of the' condenser Q24; theothercele ment' offwhich' is connected tc .=t`erminal`G of? the source'.-y .i 'When the third fullfhelght; projection-,on cam wheel-:INT engages, contact; member; thea cin-Ay M cuit'- off battery BRTBS is interrupted. and'v that; of batteryA (iN-TB'. is establishedwiththe result that relay GRTR releases and relay ENTR again picks up. When relay GNTR picks up, contact 52 interruptsv the`r supply of energy to condenser Q24; and contact 56` ofA relay GNTR; establishes a cir.'-A cuit for supplying energy from condenser Q241tot relay 6NB2. This circuit is traced from. the left#` lia-nd element ofcondenser Q24; over back. contact 66 of' relay 6NB3, throughthel Winding of' relay 6NB2?, over front' Contact 64' of relay SNF?, back contact 58- cf relay GNFI, and over'front' contact 56' of relay ENTR' to terminal C'and thus to theother'element'ofcondenser Q24. Theeh-Y ergysupplied: to'rel'ay GNBZ. picks up the' contacts of the relay and contact 5910i relay 6NB2 interrupts the' circuit for relay ENBI so that relay SNB'I releases' promptly. Additionally, contact' t8 of? relay 6NB2 establishes the circuit for sup-- plying'energy to the` condenser Q25. This circuit is traced fromterminal B, over front Contact' 52 of relay SNTR, back contact ED of relay SNBI, front contact 68rv of relay 6NB2 andi through asymmetric unit KIS to one element ofthe' con'- denser' Q25, the other element of which is' con'- nected to terminal C of the source'. Accordingly,y a charge islbuilt up inA condenser' Q25.

Further movement of the cam'wheel IV causesthe' movable contact associated therewith' to interrupt the' circuit of battery GNTB andy toestablish the circuit of'battery GRIIB with the re'- sult' that relay ENTR', releases and' relay GRTR picks up. When relay ENTR' releases, contact 52 of relay ENTR interrupts' the' supply-of energy to' condenser Q25 a-nd contact' 56 of relay ENTR' ese tahl'ishes the circuit for supplying energy from' condenser Q25 to relay GNFS. This circuit is traced from theleftehand. element of condenser Q2 5, overback contact 6950i relay 6NF4, through the winding of' relay BNFS', over front` contactfSB of relay 6NB2., back contact 60 of relay BNBI., and over' b'a'ck contact 56 of relay GNTR to. terminal C and' thus to the other element of condenser Q25'. The energy supplied to relay 6NF3v picks up the` contacts of the relay and contact 62 of relay 6NF3V interrupts the circuit of rela?,7 BNF! andsittreleases promptly, while contact 53 of re,` lay' BNFS'A interrupts the circuit of relay SNF so that it cannot pick up, Additionally, contact-10 of? relay' SNES establishes a circuit for supplying energy to the condenser Q26; This circuit is traced from terminal B, over back Contact 52' of: relay- SNTR, backcontact' 5t of relay GNFI, back'. contact 64 ofrelay 6NF2, frontcontact 10 of relay 6NF3, and throughy asymmetric unit K11 to one: element of; condenser Q26, the' other element of'. which iszconnected to' terminal C. As a result;` a chargeof'energy: is built' up in: condenser' Q26.y

Wherrthe movable contact associatedlwith cam Wheel IV engages the fourth projection' of' full height, it interrupts the circuit of battery GRTB and establishes the circuit of battery SNTB.. As a result, the relay ERTR releases and relay ENTR picks'up'. When relay GNTR picks up, contact 52 interrupts the supply oi` energy to condenser Q26 and contact 56 of' relay ENTR establishes a circuit forsupplyingy energy from condenser Q26 to relay SNBS. This circuit is traced` from theleft'- hand'xelement of condenser Q26, over'back contact' 1i of relay 6NB4, throughv the Winding of relay SNE-lover' front contact. 'l0' of relay SNES; over hack. Contact: 64 of` relay` GNFZ, over: back contact' 58-1 oi relay ENE! and over frontcontact 5 6. of," relay to.l termina-'1C'. and-thusto the' other element oi.' condenser Q26. The energy supplied to relay 6NB3 picks up the contacts of the relay and contact 66 of relay 6NB3 interrupts the circuit by which rectier KI is connected across the terminals of the Winding of relay 6NB2 so that relay 6NB2 releases promptly. Additionally, contact 12 of relay 6NB3 establishes the circuit for supplying energy to the condenser Q21. This circuit is traced from terminal B, over front contact 52 of relay ENTR., over back contact 60 of relay GNBI, over back contact 68 of relay 6NB2, over front contact 12 of relay 5NB3, and through the asymmetric unit Kl8 to one element of condenser Q21, the other element of which is connected to terminal C. Accordingly, a chargevof energy is built up in condenser Q21.

1 Further movement of the cam wheel IV causes the movablevcontact associated therewith to interrupt the circuit of battery BNTB and to establish the circuit of battery BRTB With the result that relay GNTR releases and relay BRTR picks up. When relay SNTR releases, contact 52 of relay SNTR interrupts the supply of energy to condenser Q21 and contact 56 of relay ENTR establishes the circuit for supplying energy to relay 6NF4 from the condenser Q21. This circuit is traced from the left-hand element of condenser Q21, through the winding of relay 6NF4, over front contact 12 of relay ENB3, over back contact 68 of relay 6NB2, over back contact 60 of relay GNBI, and over back contact 56 of relay BNTR to terminal C and thus to the other element of condenser Q21. The energy supplied to relay 6NF4 picks up the contacts of the relay and contact 69 of relay 6NF4 interrupts the circuit for connecting the rectier KI 6 across the terminals of the winding of relay 6NF3 so that it releases 'promptly while contact 54 of relay 6NF4 interrupts the circuit of relay ENFI so that relay BNF! remains released and cannot pick up at this time. Additionally, contact 13 of relay 6NF4 establishes the circuit for supplying energy to the condenser Q28. This circuit is traced from terminal B, over back contact 52 of relay 6NTR, over back Contact 58 of relay BNFI, over back contact 64 of relay 6NF2, over back contact 10 of relay 6NF3, over front contact 14 of relay GRTR, over front contact 13 of relay 6NF4, and through asymmetric unit KIS to one element of condenser Q28, the other element of which is connected to terminal C. As a result, a charge of energy is built up in condenser Q28.

'Further movement of cam Wheel IV causes the moveable contact to engage a projection of one-half height, thereby interrupting the circuit i 'of battery GRTB, resulting in the release of relay IERTR.4 Whenrelay BRTR releases, its contact interrupts the supply of energy to Acondenser Q28 and establishes the circuit for supplying energy from condenser Q28 to the relay 6NB4. This circuit is traced from the left-hand element of condenser Q28, through the Winding of relay 6NB4, over front contact 13 of relay 6NF4, and over back contact 14 of relay BRTR to terminal C and thus to the other element of condenser Q28. The energy supplied to relay 8NB4 picks up the contacts of the relay, and contact 1I of relay 5NB4 interrupts the circuit for connecting rectier KI1 across the terminals of the winding of relay 6NB3 so that this relay will release promptly and its contact 12 interrupts the circuit for supplying energy from condenser Q21 to relay 6NF4 'and it releases after a short time interval.

Further movement of the cam wheel IV causes the movable contact associated therewith to establish the circuit of battery SRTB with the result that relay SRTR picks up. When relay SRTR picks up, its Contact 14 interrupts the circuit for supplying energy from condenser Q28 to the relay 6NB4, and relay 6NB4 thereafter releases.

- Because of the snubbing eiect of the recti- 6NB4 delay release of these relays only for a limited period and these relays will release before the relay NTR picks up to start a new cycle of operation.

When the movable contact associated with the cam wheel IV engages the second projection of half height, the circuit of battery GRTB is interrupted and relay GRTR releases, and When the contact moves into the next depression of cam wheel IV, relay SRTR again picks up.

Further movement of cam wheel IV causes movable contact associated therewith to again be engaged with the first projection of full height, and the complete cycle described above is again repeated.

,From the foregoing it will be seen that during one revolution of the cam wheel IV the relay ENTR picks up and releases four times, and that as a result of the operation of relay ENTR the stepping relays NF and NB are picked up and released in sequence. Each stepping relay must pick up to prepare the circuit for the succeeding relay, while each stepping relay must release to prepare a circuit for another of the relays. As operation of the stepping relay chain requires each stepping relay to pick up and to release, it follows that each operation of all of these relays is fully checked-and failure of any one of these relays to pick up or release will prevent some of all of the other stepping relays from picking up. As explained below, the display of permissive indications by the wayside signals is dependent on continued operation of the stepping relays, and as failure of any one of the stepping relays to operate as intended stops operation of the relay chain it follows that any failure of the stepping relay chain will not result in a hazardous condition;

The 'repeater relays SFIP, GFZP, 6F3P and 6F4P are each supplied with energy over a front contact of one of the stepping relays GNFI, BNF2, 6NF3 and 6NF4, respectively, these contacts being designated by the characters 15a, 15b, 15a, and 15d, in the order named. Each `of the repeater relays is provided with a condenser, which condensers are designated Q3 I, Q32, Q33 and Q34, respectively. The circuits governed by the stepping relays for supplying energy to the repeater relays and the associated condensers, and for connecting the condensers across the terminals of the Winding of the repeater relays include front contact 5D of relay BRBR so that these circuits are established when and only when relay, GRBR. is picked up.

' During the cycle of operation described above, it will not noted that relays SNFI, BNFZ, 6NF3 and 6NF4 pick up and release once during each control code cycle. As a result, each of the repeater relays BFIP, 6F2P, 6F3P and 6F4P is energized, and each of the condensers Q31, Q32, Q33 and Q34 is charged once each cycle. vThese repeater relays and the condensers are selected so that the energy stored in a condenser is suf` flcient to retain the associated relay in its pickedup condition for the duration of one complete control code cycle.

Accordingly, at this time energy is supplied to the upper green lamp G of the signal GS by the circuit which is traced from terminal B, over front contact 'It of relay BFIP, over iront contact 'll of relay EFZP, over front contact T8 of relay 6F3P, over front contact '19 of relay 6F4P, and through the upper lamp G to terminal C. Additionally, energy is supplied to the lower red lamp R by the circuit which is traced from terminal B, over front contact 82 of relay BFIP, front contact 83 of relay SFZP, front contact 84 of relay BFSP, front contact 85 of relay BFdP, and through the lower lamp R to terminal C. As a result, the signal displays an aspect of greenover-red, which indicates clean From the foregoing it is clear that the circuits for controlling the lamps of the signal BS are arranged so that all of the repeater relays must be energized to cause the signal -to display it clear indication. Accordingly, if for any reason one of the repeater relays fails to pick up, the signal cannot display its clear indication but will display a restrictive indication. This provides a further check that the stepping relays are operating as intended since all of the repeater relays will not be picked up unless the stepping relays are operating properly.

The repeater relays SFIP, SF2?, SFSP and GF4? also control the supply of coded energy to the rails of section 5T, in substantially the same manner as the corresponding relays 'IFIP, TF2?, 1F3P and 1F4P control the supply of coded energy to the rails of section 6T. In order to simplify this disclosure the means for supplying coded energy to the rails of section 5T has not been shown.

With the equipment operating as described above, it will now be assumed that a train, moving from left to right, passes signal BS and enters section 6T. The wheels and axles of the train shunt the relays ENTR and GRTR, and these relays release and remain released as long as the train occupies section 6T.

As previously pointed out, the relays BRFR and BRBR release in a Very short time after relay BRTR stops operating. When relay ERBR releases, its front contact 50 interrupts the circuits for supplying energy to the repeater relays EFIP, 5F21, 6F31), and 6F41 while it also interrupts the circuits for connecting the condensers across the terminals of the windings of the repeater relays and these relays release promptly. The upper red lamp R of signal BS is now supplied with energy by a circuit including back Contact 1B of relay BFIP, and the circuit previously traced for supplying energy to the upper green lamp G of signal S is interrupted by contact 'I6 of relay BFIP, while the lower red lamp R is supplied with energy by a circuit including the back contact 82 of relay BFIP. Accordingly, While section 6T is occupied, the signal BS will display an aspect of red-over-red, indicating stop The relays 1F4P, 1F3P, TFZP and 'lFlIP are governed in a similar manner to that described above for relay 6F41), 6F3P, 6F2P and GFIP, and accordingly, when the train enters section 7T, the relays 1F4P, 1F3P, 'IFZP and IFIP release.

When the train vacates section 6T, coded energy is again supplied to the track relays ENTR and GRTR. At this time the energy supplied from batteries BNTB and BRTB to the section rails is governed by Vthe contact associated with cam wheel I and is supplied over a circuit which includes back contact 45 of relay 1F41), back con-l tact 81 of relay '1F3P, back contact 88 of relay- 1F21), and back contact 89 of relay 'IF'IR During each revolution of cam wheel I one impulse of positive polarity and six impulses of negative polarity are supplied to the rails of section 6T, and since the cam wheel rotates continuously, the coded energy supplied to relays ENTR and GRTR consists of a succession or' negative impulses separated by "o1l` periods, with every sixth ort period being replaced by a positive impulse.

The relay ERTR will again operate its contacts on the reception of impulses o1" negative energy, and as previously described, relays BRFR and SRBR will be energized and their contacts will pick up. When contact 5U of relay BRBR picks up, it again establishes the connection it governs for controlling the repeater relays BFIP, FZP, 6F3P and 6F4P.

When the movable contact associated with cam Wheel I engages the proyection of full height, the circuit of battery BRTB is interrupted and the circuit of battery GNTB is established and as a result relay SRTR releases and relay ENTR picks up.

When relay ENTR picks up, energy is supplied to the condenser Q2I over the circuit previously traced. On continued movement of the cam wheel I, its movable contact interrupts the circuit of battery BNTB and establishes the circuit of battery SRTB, with the result that relay GNTR releases, and relay SR'IR picks up. when relay SNTR releases, the energy stored in condenser Ql is suppiied to relay iNFl and the relay contacts pick up. After a time interval the energy supplied from condenser Ql is ineffective to hold the relay 6NFI picked up and it releases. The equipment is arranged and proportioned so that the energy supplied from condenser QZI to the relay BNFI will keep the relay contacts picked up for an interval equal to one step in the code cycle, but will not hold it picked up for a substantially longer period. Accordingly, relay GNFI picks up and remains picked up for a short time, but releases before relay GNTR picks up again.

During the period in which relay BNF! is picked up, energy is supplied to condenser Q22 by the circuit including back contact 52 of relay 6NTR and front contact 58 of relay NFl and a charge is built up in condenser Q22. However, since relay ENTR remains released for the remainder of the control code cycle, and as relay GNF! releases after a short period, the circuit for supplying energy from condenser Q22 to relay BNBI is not established and relay SNBI remains released, while the energy stored in condenser Q22 is dissipated by the resistor connected across its terminals. Accordingly it will be seen that at this time the relay BNF! will be picked up and released once during each control code cycle. The relay BFIP will therefore be supplied with energy by the circuit governed by the front contact 15a of relay GNFI, which circuit is established once during each control code cycle. The energy supplied to the condemer Q3| Iwill retain the relay GFIP picked up during the intervals between the supply of energy thereto. The relays 6F21, BFSP and 6F4P are not supplied with energy and their contacts remain released.

At this time, therefore, the top yellow lamp Y of signal BS is supplied with energy by the circuit which is traced from terminal B, over front contact 1E of relay SFIP, back contact 'l1 of relay GFZP, and through the upper yellow lamp Y of signal 'BS to terminal lC. Additionally, the lower red lamp R ci signal 55S is supplied with energy by the circuit including front contact S2 of relay BFlP, back contact 83 of relay 6F21), and through the lower red lamp R of signal S to terminal C. The signal therefore displays an aspect of yellowover-red, indicating approach next signal pre pared to stop.

As the train under discussion progresses, the relays IFIR 1F2P, 'IF'SP and lFllP are progressively energized in the order named- When the train Vacates section 1T, the contact 89 of .relay 'IFlP is picked up yso that the contact operated by cam Wheel I no longer governs the supply of energy to section GT, and energy is now supplied to the track section 6T by a circuit including back'contact d5 yof relay lFllP, back contact 8l of relay 1F31), back contact 38 of relay TFZP, `front contact te vof relay Fl-P, and the movable contact of cam Wheel II.

The construction of the cam Wheel II is such that during each revolution of this Wheel there are supplied to the track rails six impulses of energy of reverse polarity separated by two perio'd's in which impulses of energy of normal polarity are supplied to the track rails and four periods in which no yenergy is supplied to the track rails.

When the movable contact associated with cam Wheel II engages the first projection of lull height, the circuit of battery SRTB is interrupted, and the circuit of battery BNTB is established, and as a result,the relay GRTR releases and the relay ENTR pick-s up.

When relay SNTR picks up, the circuit previously traced for supplying energy to the con denser Q2| is established and a charge of energy is built up in Acondenser Q2 l. Further movement of 'the cam wheel II causes the movable contact to interrupt the circuit of battery ENTB and establish the circuit of battery lliRTB so that relay GNTR releases and relay BR'IR picks up. When relay ENTR releases, the circuit previou-sly traced for supplying energy to the relay ENFl from condenser QZl is established, and relay GNFi picks up. Additionally, condenser Q22 is supplied Iwith energy by 'the circuit 'previously traced which includes back contact 52 of relay ENTR and front Contact 53 of relay SNFI.V Accordingly, a charge is built up on condenser Q22.

Further movement of the cam Wheel II causes the movable contact to engage the second projection Aof full height, so that the circuit of battery SRTB is interrupted `and the circuit of battery SNTB is established, with the result that relay SR'IR releases and relay ENTR picks up. When relay ENTR picks up, the circuit previously traced for supplying energy to relay f"cNBl from condenser Q22 is established and relay BNBI picks up, establishing the circuit for supplying energy to condenser Q23, which circuit includes front contact 52 of relay iN'ITrt vand iront contact Si! of 'relay GNBI. As a result, a charge of energy is built up in condenser Q23. When further movement of the cam Wheel II causes the moviable contact to be disengaged from the second projection of full height, the circuit oi battery SNTB is interrupted, and the circuit of battery GRTB is established, With the result that relay ENTR releases, and relay R'IR picks up. When relay ENTR releases, it establishes the circuit .previously traced for supplying energy to the relay 6NF2 from condenser Q23 and relay GNFZ picks up. When relay fiNF picks up its contact 51 interrupts the circuit of relay BNFl and also interrupts the lcircuit for connecting the rectifier;

K12 across the terminals of the winding of relay NFl so the relay contacts release quickly. When relay SNFI releases it establishes the circuit pre viously traced for supplying energy to condenser Q24, which circuit includes back contact 52 oi relay ENTR, back contact 58 of relay tNFI, and contact 64 of relay BNFZ. Accordingly, a charge of energy is built up in condenser Q24, but since relay ENTR does not again pick up to `esablish the circuit for supplying energy from condenser Q24 to relay GNBZ, the .relay BNB? vremains vreleased. The lcircuit for supplying energy to condenser Q2G is interrupted on subsequent 'releasev of relay BNF?, and the energy stored iin condenser G2213 is dissipated by the resistor connected across its terminals.

As explained above, on release 'of relay @NTB following its second pickedeup period the circuit is established `for supplying energy .from the condenser Q'23 to relay ENFZ. As relay SNT-R 'thereafter vremains released Vfor a substantial period the energy stored in the condenser Q23 is dis/- charged through the Winding 'of relay 6NF2 and the contacts of relay BNFZ release before relay ENTR picks up again. Accordingly, when the relay ENTR is picked 'up during the succeeding control code cycle 'the operation of the stepping relays starts -from the beginning and not from an intermediate point in the chain,

From the foregoing it will be seen vthat when the cam Wheel II governs the supply of coded energy to section 6T, the relays GNFI and SNFQ are picked up and release once 'dur-ing each control code cycle, 'While the relays BRIR and SRBR remain 'picked 'up continuously. As a result, energy is supplied at intervals to the repeater relays 6Fl? and SFZP and their associated condensers QSI and Q32. The relays 5F31D and FllP are not supplied with energy at this time and their contacts remain released.

At this time, therefore, the upper yellow lamp Y of signal SS is supplied with energy over the circuit including front contact 'I6 of relay FlP, front contact Il of relay BFZP, and back contact 'I8 of relay BFSP, While the lower yellow lamp Y of signal A'5S is supplied with energy over the circuit including front contact 82 of relay GFIP front contactr of relay BFZP, and back contact 84 of relay GFSP. The signal ES, therew fore, displays an 'aspect of yelloW-oVer-yellow, indicating approach second 'signal prepared to stop.

l When the train under consideration vacates the section in advance of section 7T, the relay 'IFZP picks up, interrupting the circuit governed by cam Wheel II and establishing 'the circuit governed by cam Wheel III. Coded energy is now supplied to section 6T 'over the circuit which includes Yback contact 45 of relay 713413, back contact 8l of relay 7F3P', front contact 88 of relay 1F21?, and the movable contact associated With cam Wheel I'I. At this time, therefore, during' each control 'code cycle 'there are supplied to the rails of section 6T, six impulses of energy of negative polarity which are separated by three impulses of energy of normal polarity Aand by three oil intervals. The supply of impulses of negative polarity to `relay R'IR causes this relay to continue operating, andas a result, the relays SRFR and BRBR are maintained picked up.

When the movable Contact associated with cam Wheel III engages the rs't projection 'of full height, the circuit vof battery ENTB is established and the circuit of battery SRTB is interrupted,`

with the result that relay SNTR picks up and relay SRTR releases. condenser Q2l is charged, as previously explained. On further movement of the cam wheel III, the circuit of battery GNTB is interrupted and the circuit of battery ERTB is established, so that relay ENTR is released and relay BRTR picks up. When relay SNTR releases, the circuit for supplying energy to relay BNFI from condenser Q2! is established and relay BNF! picks up. The condenser Q22 is then supplied with energy over the circuit including back contact 52 of relay BNTR and the front contact l58 of relay BNFI.

When the movable contact engages the second projection of full height on cam Wheel III, the circuit for battery BRTB is interrupted and the circuit for battery BNTB is established, as a result of which the relay ENTR is picked up and the relay BRTR is released. When relay ENTR picks up, the energy stored in condenser Q22is supplied to relay BNBI over the circuit previously traced, and relay SNBI picks up, thereby establishing the circuit for supplying energy to con-v denser Q23, while during this picked up period of relay ENTR energy is supplied to condenser Q2I. As a result, a charge of energy is built up in condensers Q2! and Q23.

Further movement of cam wheel III disengages the movable contact from the second projection of full height, interrupting the circuit of battery BNTB, With the result that relay GNTR is released and relay SRTR is picked up. When relay ENTR releases, the circuit previously traced for supplying energy to condensers Q2|l and Q23 is interrupted, and relay 6NF2 is supplied with energy from condenser Q23 over the circuit previously traced. As a result, relay BNF2 picks up and its contact l interrupts the circuit for supplying energy from condenser Q2I to relay SNFI and for connecting rectifier KIZ across the terminals of the Winding of relay BNFI with the result that relay GNFl releases promptly and the energy stored in condenser Q2! is dissipated by the resistor connected across its terminals. Additionally, when contact 64 of relay 6NF2 picks up, energy is supplied to condenser Q24 over the circuit previously traced. Accordingly, a charge of energy is built up in condenser Q24. y

When the movable contact associated With cam Wheel III engages the third projection of full height, the circuit of battery GRTB is interrupted, and the circuit of battery ENTB is established, with the result that relay SRTR releases and relay ENTR picks up. During this third pickedup period of relay ENTR, energy is supplied to relay 6NB2 from condenser Q24 over the circuit previously traced. When relay 6NB2 picks up, its contact 59 interrupts the circuit for connecting the rectiiier K13 across the terminals of the winding of relay BNBI so that relay BNBI releases. Additionally, when relay SNBZ picks up, energy is supplied over its front contact 68 to the condenser Q25 and a charge of energy is built up in condenser Q25.

Further movement of the cam wheel III disengages the movable contact from the third projection so that the circuit of battery GNTB is interrupted, and the circuit of battery BRTB is established. Accordingly, the relay BNTR releases and relay BRTR picks up. When relay ENTR releases, energy is supplied to relay ENF3 froml condenser Q25 and relay 6NF3 is picked up. When relay 6NF3 picks up, its contact 53 interrupts the circuit of condenser Q2! so that relay BNF! is certain to remain released, and

When relay SNTR picks up, the,

contact 62 of relay 6NF3 interrupts the circuit for connecting rectiner KM across the terminals of the winding of relay 6NF2 so that relay 6NF2 releases promptly, When relay BNFZ releases,

'. energy is supplied to condenser Q28 over the circuit which includes front contact 10 of relay 6NF3. Accordingly, a charge of energy is built up in condenser Q26. However, relay ENTR does not pick up again during the remainder of the -l code cycle and therefore does not establish the circuit for supplying energy from condenser Q26 to relay 6NB3 so relay GNBB remains released. After a short time interval, relay 6NF3 releases, and its c'ontact 'lll interrupts the supply of energy 1f to condenser Q26, and the charge of energy in the condenser is thereafter dissipated through the resistor connected across the terminals of condenser Q26. Since relay 6NB3 does not pick up, the circuits for charging condensers Q21 and i Q28 are not established, and as a result the relays 6NF4 and 6NB4 do not pick up.

The relay GRTR is thereafter picked up and released during the portion of the control code cycle remaining in this revolution of the cam wheel III, and the movable contact associated with cam wheel III then engages the first projection of full height, and the cycle described above is repeated.

It will be seen, therefore, that during the time that cam Wheel III governs the supply of energy to the track section 6T, the relay BRTR operates continuously, being picked up and released six times during each control code cycle, so that relays GRFR and BRBR are picked up, and the connection governed by contact 50 of relay SRBR for supplying energy to the repeater relays BFIP, 6F2P, 6F3P and SP4? is established. Additionally, the relays GNFI, GNBI, 6NF2, 6NB2 and 6NF3 are picked up and released once during each control code cycle. When relays GNFI, ENFZ and 6NF3 pick up, energy is supplied to their respective repeater relays and associated condensers, so that at this time, relays GFIP, BFZP and 6F3P are picked up.

At this time, therefore, the upper yellow lamp Y of signal BS is supplied with energy by the circuit which is traced from terminal B, over front contact 'l5 of relay 6Fl?, front contact 'l1 of relay 6F2P, front Contact 78 of relay GFSP, back contact 'i9 of relay 6F41?, and through the upper yellow lamp Y to terminal C. Also, the lower green lamp G of signal BS is supplied with energy by the circuit which is traced from terminal B, over front contact 82 of relay GFIP, front contact 83 of relay 6F2P, front contact 84 of relay GFSP, back contact 85 of relay 6F4P, and through the lower green lamp G of signal GS to terminal C. The signal GS therefore displays an aspect of yellow-over-green, indicating proceed approaching next signal at medium speed.

When the train under consideration progresses further, the relay 1F3P picks up, interrupting the circuit governed by cam Wheel III and establishing the circuit governed by cam wheel IV. When the train progresses still further, the relay 1F4P picks up, which maintains the circuit governed by cam wheel IV. The operation of the equipment at this time is the same as that originally described, and the equipment is restored to its normal condition with signal ES displaying an aspect of green-over-red, indicating clean Although I have shown and described a codedl 23 tion whereby four ydistinctive code cycles are employed., it is to be understood that the number oi" code cycles may be varied as desired, with corresponding changes in the number of relays necessary to decode the code cycle steps.

.From the 'foregoing it will be seen that the system shown in Fig. 4. operates on a count code basis to govern the Wayside signals in accordance with the number of impulses of energy of normal polarity supplied kover the .rails of a track section during one code cycle. In addition, it will .be seen that regardless of trafiic conditions in advance 'impulses oi energy of reverse polarity are supplied over the section rails at uniform rela-- tively frequent intervals and oper-ate the .relay BRTR to keep the relays BRFR and GRBR picked up. As the relay tR'IR operates at a rapid rate the release delay period of the relays ERF-R and BRBR is relatively short and on entrance of a train into section 6T these relays will release quickly and put. signal S to stop. Accordingly, the shunting 'time of the equipment .for a track section is not governed by the length of the code cycle and this may be made as vlong as desired to provide numerous -distinctive indications without objectionably delaying the display of the stop indication after entrance of a train into the section.

Although .I have herein shown and described only a few 'forms oi coded signaling apparatus embodying my invention, it is understood that various changes and modications may be made therein within the scope of the appended claims without departing from the spirit and Vscope of my invention.

.Having thus described my invention what I claim is:

1. In combination, a code following relay having a movable contact operable between a iirst 'position in which it engages a rst stationary contact which is connected to the rst terminal of a source of direct current and a second position in which it engages a second stationary contact which is connected to the second terminal of said so-urce, a condenser, a code detecting relay, a circuit including said code vfollowing relay movable contact and operative when said contact is in its first position to connect said condenser across the terminals of said vsource independently of the winding of said code detecting relay, and a circuit including said code following relay movable contact and operative when said contact .is in its second position to connect said condenser across the terminals of the Winding of said code detecting relay.

2. In combination, a. source of direct current having a rst and a second terminal, a code detecting relay having a winding having a .first and a1 second terminal, a condenser having its first terminal connected to the second terminal of said source of current and having its second terminal connected to the second terminal of the winding of said code detecting relay, and a code following relay having a movable contact operable between a first position in which it establishes a connection independent of the winding of said code detecting relay from the rst terminal of said source 'of direct current to the second terminal of said condenser and a second position in which it establishes a connection from the second terminal of said condenser to the iirst terminal of said condenser and including in series yto therewith the winding of said code detecting re- 2 ing a movable contact which .is moved between'a first position in which it engages a first stationary contact and a second position in which it engages a second stationary contact, a condenser having a first and a lsecond terminal, a source of direct current having its iirst terminalk connected to said .nrst stationary -contact and having its second terminal connected to the first terminal 'of said condenser and also to said second stationary contact, a code detecting relay having one terminal of its winding connected to said movablevcontact and having the other terminal of its winding connected to the second terminal of said condenser, and means independent of the winding of said code detecting relay for supplying energy from said source to said condenser when the movable contact of said code following relay engages lsaid `rst stationary contact.

4. In combination, a code following relay having a 'first and a second movable contact operated substantially .in synchronism, said contacts being moved between a rst position in which the first movable contact engages a nrst stationary contact and the second movable contact engages a -second stationary contact and a second position in which ther .first movable contact engages a third stationary contact and the second movable contact engages a fourth stationary contact, a condenser having a first and a second terminal, a source of directl current having its iirst terminal connected to said first stationary contact and .having its second terminal connected to the first terminal of said condenser and also 'to said third stationary contact, a code detecting relay Vhaving one terminal of its winding connected to said fourth stationary contact and having `the other terminal of its winding connected to the second terminal of said condenser and also connected to said second stationary contact, said i'lrst and second movable contacts being connected so that when they occupy their rst posi- 'tion energy is supplied to said condenser from said source independently of the winding of said code detecting relay, and a circuit governed by a contact of said code detecting relay.

5. In combination, a. series of relays, a series of condensers, lone each of said condensers being associated with each of the relays in said series, a ycode following .relay having contacts movable between a first and a second position, a circuit for supplying energy to the condenser associated with each of vsaid relays including a contact oi said code following relay closed in its iirst position, the circuit for supplying energy to each yoi said condensers except the condenser associated with the .first relay of said series including a front contact of the preceding relay in said series, a discharge circuit for supplying energy from each of said condensers to the associated relay, each of said discharge circuits including a contact of said code following relay closed in its second position., the discharge'circuit for supplying energy to each of said relays except the rst relay in said series including a fron-t contact of the preceding relay in said series, and control means selectively governed by said series of relays.

6. In combination, a series of stepping relays, a series of condensers, one each of said condensers being associated with each of the stepping relays in said series, a code following relay having contacts movable between a. rst and a second position, a iirst auxiliary relay, a circuit including a back contact of said first auxiliary relay for supplying energy to the condenser associated with each of said :stepping relays including aV con- 25 tact of said code following relay closed in its first position, the circuit for supplying energy to each of said condensers except the condenser associated with the first relay in said series including a front contact of the preceding relay in said series, a discharge circuit including a back contact of said first auxiliary relay for-supplying energy from each of said condensers to the associated stepping relay, each of said discharge circuits including a contact of said code following relay closed in its second position, the discharge circuit for supplying energy to each of said relays except the rst relay in said series including a front contact of the preceding relay in said series, a condenser associated with said first auxiliary relay, a circuit including a contact of said code following relay closed in its first position for supplying energy to the condenser associated with said rst auxiliary relay, said last-named circuit including a front contact of the last relay r in said series, which contact is by-passed by a front contact of said first auxiliary relay, a cir- `cuit including a contact of said code following relay closed in its second position for supplying energy from the condenser associated with said first auxiliary relay to said relay, said last-named circuit including a front contact of the last stepping relay in said series, which contact is bypassed by a front contact of said first auxiliary relay, a second auxiliary relay having a condenser associated therewith, a circuit including a front contact of said first auxiliary relay and a contact of said code following relay closed in its second position for supplying energy to the condenser associated with said second auxiliary re- Iy` lay, a circuit including a front contact of said first auxiliary relay and a contact of said code following relay closed in its first position for supplying energy to said second auxiliary relay from the condenser associated therewith, and a circuit l controlled by a contact of said second auxiliary relay.

7. In combination, a section of railway track through which traflic normally moves in a given direction, means at the exit end of said section for `supplying to the section rails detector code energy comprising impulses of energy of reverse polarity separated by time intervals, means at the exit end of said section for supplying to the section rails in said intervals recurring cycles of one or another of a plurality of different numbers of impulses of energy of normal polarity, a first and a second code following track relay located at the entrance end of said section and operated by energy supplied over the section;

rails, said first track relay having a contact which is moved from a first to a second position only in response to energy of normal polarity and said second track relay having a contact which is moved from a first to a second position only in response to energy of reverse polarity, a series of stepping relays each having an asymmetric unit connected across the terminals of its-winding and 'each being connected in series with a condenser,

circuit means governed by contacts of said first relay, circuit means effective in one position of the contacts of said second track relay for supplying energy to said last named condenser through the asymmetric unit connected across the terminals of said code detecting relay, circuit means efective in the other position of the contacts of said second track relay for supplying energy from said last named condenser to the Winding of said code detecting relay, a signal governing entrance of traflic into said track section, said signal being controlled by said code detecting relay so that when said code detecting relay is released said signal displays its most restrictive indication and when said code detecting relay is picked up said signal displays one or another of a plurality of different permissive indications according to the number of said stepping relays which are energized during each control code cycle.

8. In a coded signaling system, in combination, a section of railway track through which traffic normally moves in a given direction, means at the exit end of said section for supplying to the rails of said section recurring cycles of control code comprising impulses of energy of a first type, means governed by traic conditions in advance of said section for causing each of said control code cycles to include one or another of a different number of energy impulses, means at the exit end of said section for supplying to the rails of said section detector code comprising impulses of energy of a second type, said impulses of detector code energy being of such duration and being supplied at such intervals that a plurality of such impulses are supplied during one cycle of said control code, a first and a second code following track relay located at the entrance end of said section and operated by energy supplied over the rails of said section, said iirst code following relay being responsive only to energy of said first type and said second code following relay being responsive only to energy of said sec-` ond type, a first code detecting means governed by said first code following relay and selectively responsive to the number of times said first code following relay is operated during each of said control code cycles, a second code detecting means governed by said second code following relay, a signal governing entrance of traiiic into said section, and means governed by said second decoding means for holding said signal at stop or for causing said signal to display one or the other of a plurality of different permissive indications selected by said first code detecting means.

9. In a coded signaling system, in combination, a section of railway track through which traiiic normally moves in a given direction, means at the exit e-nd of said section for supplying to the rails of said section recurring cycles of control code comprising impulses of energy of a first type, means governed by traic conditions in advance of said section for causing each of said control code cycles to include one or another of a different number of energy impulses, means at the exit 'end of said section for supplying to the trails of said section detector code comprising impulses of energy of a second type, said impulses of detector code venergy being of such duration and being supplied at such intervals that a plurality of such impulses are supplied during one cycle of said control code, code following means at the entrance end of said section operated by Venergy supplied over the rails of said section, said code following means being selectively responsive to energy of said rst` or said second type, a rst code detecting means governed by response i o said code following means to energy of said rsttype and selectively responsive to the number of times said code following means is operated by energy of said rst type during each of said control code cycles, a second 'code detecting means governed by response of said code following means toV energy of said second type, a signal governing entrance of traic into said section,

and. means governed by said second. decoding means for holding said signal at stop or for causing said signal to display one or the other of a plurality of diierent permissive indications selected by said rst code detecting means.

l0. In a coded signaling system, in combination, a section of railway track through which traiilc .normally moves in a given directi-on, means at the exit end of said section for supplying to the rails of said section detector code energy comprising impulses of energy separated by intern vals, means at the exit end or said section and eiective during said intervalsfor supplying to the rails of said section impulses of control code energy, the impulses of control code consisting of energy of a first type and the impulses of detector code consisting of energy of a second type, means governed by trafc conditions in advance of said section for governing the supply of impulses of control code energy to the rails of said section to cause them to be supplied in recurring cycles each of which includes one or another of a diierent number of energy impulses, code following, means at the entrance end of said secvtion operated by energy supplied over the rails ysaid relay being sufficiently slow in releasing to remain picked up only for a, period slightly longer than an interval between successive impulses of energy of said second type, a signal governing entrance of traflic into said section, and means 4effective when said slow release relay is released for causing said signal to display its stop indication and effective when said slow release relay is picked up to cause said signal to display one or another of a plurality of different permissive indications selected by said rst code detecting means.

11. In a coded signaling system, in combination, a section'of railway track through which traffic normally moves in a given direction. means at the exit end of said section for supplying to .the rails of said section detector code energy comprising impulses of energy separated by intervals, means at the exit end of said section and effective during said intervals for at times supplying to the rails of said section impulses of control code energy, the impulses of control code consisting of energy of one polarity and the impulses of detector code consisting of energy of the other polarity, means governed by traiiic conditions in advance of said section vfor gov- -ermng the supply of impulses of control code energy to the rails of said section to cause them to be supplied in recurringy cycles, each of which includes one or another of a diierent number of energy impulses,v code following means at. the entrance. end of said section operated by energy supplied over the rails of said section and selectively responsive to the polarity of such energy, a lirst code detecting means governed by response of said code following means to energy ci said other polarity and selectively responsive tothe number of times said code following means is operated by energy of said other polarity during each of said control code cycles, asecond code detecting means comprising a slow release relay governed by response of said code following' means to energy of said one polarity, said relay being suihciently slow in releasing to remain picked up only for a period slightly longer than an interval between successive impulses of energy of said one polarity, a signal governing entrance of traine into said section, and means governed by said rst and second code detecting means for controlling said signal, said means being effective when said slow release relay is released to cause said signal to display its most restrictive indication and being eiective when said slow release relay is picked up to cause said signal to display one or another of a plurality of diierent permissive indications selected by said iirst decoding means.

l2. In a coded signaling system, in combination, a section of railway track through which trame normally moves in a given direction, means at the eXit end or" said section for supplying to the rails of said section detector code energy comprising impulses of energy separated by intervals, means at the exit end of said section and effective during said intervals for at times supplying to the rails of said section impulses of control code energy, the impulses of control code consisting of energy of one polarity and the impulses of detector code consisting of energy of the other polarity, means governed by traiiic conditions in advance of said section for governing the supply of impulses of control code energy to the rails of said section to cause them to be supplied in recurring cycles, each of which includes one or another of a different number of energy impulses, a rst and a second code following track relay at the entrance end of said section operated by energy supplied over the section rails, said rst track relay being responsive only to energy of said one polarity and said second track relay being responsive only to energy of said other polarity, a chain of counting relays governed by said rst track relay so that during each control code cycle successive relays are picked up on successive operations of said first track relay with the result that the vnumber of said counting relays which are energized varies in accordance with the number of control code impulses in each control code cycle, a slow release relay energized in response to operation of vsaid second track relay, said slow release relay being suiiicientlyl slow in releasing to remain picked up only for a period slightly longer than an interval between successive impulses'of energy of said one polarity, a signal governing entrance of trafc into said section and means gov.- erned by said slow release relay and by said counting relays for controlling said signal, said means being effective when said slowrelease relay is released to cause said signal to display its most restrictive indication and being eiective when said slow `release relay is picked up to cause said signal to display one or` another `of a pluralitr 0f different permissive indications selected 29 in accordance with the number of said counting relays which are energized during each control code cycle.

13. In combination, a code detecting relay, a source of direct current, a condenser, a code following relay operable recurrently between a rst position in which a first stationary contact is engaged by the operation of said relay to establish a circuit connection to one terminal of said source and a second position in which a second stationary contact is engaged thereby to establish a circuit connection to the other terminal of said source, said connections being so arranged that the source is effectively short circuited in the event both stationary contacts are engaged at the same time, a circuit independent of the winding of said code detecting relay but including said source, said condenser, and the connection established when said rst stationary contact is engaged for charging said condenser from said source, and a circuit independent of said source but including said condenser, the winding of said code detecting relay and the connection established when said second stationary contact is engaged for discharging said con- .e

denser through the Winding of said code detecting relay.

14. In combination, a code detecting relay, a source of direct current, a condenser, a code following relay operable recurrently between a rst ,Y

position in which a first stationary contact is engaged by the operation of said relay to establish a circuit connection to one terminal of said 30 source and a second position in which a second stationary contact is engaged thereby to establish a circuit connection to the other terminal of said source, said connections being so arranged that the source is effectively short circuited in the event both stationary contacts are engaged at the same time, a circuit for charging said condenser by energy from said source which includes said condenser and source in series with the connection established when said rst stationary contact is engaged, a circuit for discharging such stored energy through the winding of said code detecting relay which includes said winding and condenser in series with the connection established when said second stationary contact is engaged, and means associated with said winding for preventing the effective energization of said code detecting relay by energy supplied directly from said source.

HOWARD A. THOMPSON.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,197,415 Place Apr. 16, 1940 2,229,254 Nicholson Jan. 21, 1941 2,273,477 Thompson et al. Feb. 17, 1942 2,276,680 Allen Mar. 17, 1942 2,408,206 Fereday Sept. 24, 1946 

